In conventional air conditioning systems, error diagnosis or monitoring has been carried out to maintain and continue normal operation.
Possible errors in an air conditioning system include errors in a refrigerating cycle due to defective refrigerant pipes or an incorrect amount of refrigerant as well as network errors in which, for example, the air conditioning system is not correctly controlled by a bit error. It is demanded that if this type of error occurs, the cause and location of the error should be quickly identified and action such as correction should be taken. Therefore, an apparatus that can automatically determine the cause and location of the error is demanded.
Methods of determining the causes and locations of errors may be broadly classified as follows: for refrigerating cycle errors,
(1) methods by which measurement values of refrigerant temperature sensors or refrigerant pressure sensors are obtained through a network to detect abnormal values.
For network errors,
(2) methods by which waveform data of electric signals flowing in transmission lines is obtained to detect abnormal waveforms.
One proposed apparatus that diagnoses failures and errors in the refrigerating cycle as described above monitors the state of the refrigerating cycle; the apparatus retrieves the settings of sensors or control data such as abnormal signals, and performs diagnosis for failures and errors on the basis of the maximum or minimum value of pressure, temperature, or the like or daily operation trend data (see PTL 1 or 2, for example).
An air conditioning system in which a plurality of air conditioners are connected to a centralized management unit through an Ethernet (registered trademark) or the like has also been proposed (see PTL 3 or 4, for example). A diagnostic unit for the general-purpose network has also been proposed (see PTL 5, for example).